--- a/tools/unmix.py
+++ b/tools/unmix.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/python3
 """Convert a file containing a mix of python code and content into content.
 
 Write the input file to stdout. Python code included between blocks
--- a/tools/sql2extension.py
+++ b/tools/sql2extension.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/python3
 """Generate "ALTER EXTENSION" statements to package a list of SQL definitions.
 
 The script doesn't try to be a robust parser: it relies on the input file
--- a/Makefile
+++ b/Makefile
@@ -94,7 +94,3 @@ $(SRCPKG): $(PKGFILES)
 	rm -f $(SRCPKG_ZIP)
 	zip -r $(SRCPKG_ZIP) $(addprefix $(PKGNAME)/,$^)
 	rm $(PKGNAME)
-
-# Required for testing in pgxn client on PG < 9.1
-installcheck: $(INSTALLSCRIPT)
-
